From: Jonathan Wakely <jwakely@redhat.com>
Date: Fri, 17 Dec 2021 17:58:09 +0000 (+0000)
Subject: libstdc++: Compare match_results for failed regex_match
X-Git-Tag: basepoints/gcc-13~2056
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=9a2451c1013c21e76da89df89c3c8e5e6afe6154;p=thirdparty%2Fgcc.git

libstdc++: Compare match_results for failed regex_match

The regex_match_debug testsuite helper doesn't compare the
std::match_results objects after a failed match, but it should do. The
standard says that the effects of a failed match on the match-results
are unspecified, except that [conditions testable by operator==]. So we
can check that the two sets of results compare equal even if the match
failed.

libstdc++-v3/ChangeLog:

	* testsuite/util/testsuite_regex.h (regex_match_debug): Compare
	results even if the match failed.
---

diff --git a/libstdc++-v3/testsuite/util/testsuite_regex.h b/libstdc++-v3/testsuite/util/testsuite_regex.h
index 6af3d8d836fa..f2bb068024d8 100644
--- a/libstdc++-v3/testsuite/util/testsuite_regex.h
+++ b/libstdc++-v3/testsuite/util/testsuite_regex.h
@@ -150,8 +150,7 @@ namespace __gnu_test
       auto __res2 = __regex_algo_impl<_Bi_iter, _Alloc, _Ch_type, _Rx_traits,
 	   _RegexExecutorPolicy::_S_alternate, true>
 	(__s, __e, __mm, __re, __flags);
-      // __m is unspecified if return value is false.
-      if (__res1 == __res2 && (!__res1 || __m == __mm))
+      if (__res1 == __res2 && __m == __mm)
 	return __res1;
       throw std::exception();
     }